PHENOMENA ACCOMPANYING FERTILIZATION 



543 



15 



14 



-----i/li*-. 



'^m 



16 



18 



19 



-4^^'- 



.^sirL: 





20 



Fig. 227. — Oxytricha fallax; conjugation and meiosis. 2 to 9, formation and divis- 

 ion of the first meiotic nuclear spindle and separation of the twenty-four dumb-bells 

 into two groups of twelve dumb-bells each; 10 to 12, the second meiotic division; 13 

 to 15, the third division; 16, one of the pronuclei; 17 to 20, the first zygotic division. 

 (After Gregory.) 



